1. Field of the Invention
The present invention relates to a method for treating ocular inflammatory diseases in a subject in need of such treatment, which comprises administering a pharmaceutical composition comprising a therapeutically effective amount of at least one agonist of Formyl peptide receptor 2 (FPR2).
2. Summary of the Related Art
The formyl peptide receptor (FPR) family is involved in host defense against pathogens, but also in sensing internal molecules that may provide signals of cellular dysfunction. This family includes 3 members in humans and one member of this family FPR2 (also known as FPRL-1, ALXA4) is a G protein-coupled receptor that is expressed predominantly on inflammatory cells such as monocytes and neutrophils, as well as on T cells and has been shown to play a critical role in leukocyte trafficking during inflammation and human pathology (Chiang N, Serhan C N, Dahlen, S, Drazen J M, Hay D W P, Rovati E, Shimizu T, Yokomizo T, Brink, C. The lipoxin receptor ALX: Potent ligand-specific and stereoselective actions in vivo. Pharmacological Reviews 2006; 58: 463-519). FPR2 is an exceptionally promiscuous receptor that responds to a large array of exogenous and endogenous ligands, including serum amyloid A (SAA), chemokine variant sCKβ8-1, the neuroprotective peptide humanin, anti-inflammatory eicosanoid lipoxin A4 (LXA4) and glucocotricoid-modulated protein annexin A1 (Chiang N, Serhan C N, Dahlen, S, Drazen J M, Hay D W P, Rovati E, Shimizu T, Yokomizo T, Brink, C. The lipoxin receptor ALX: Potent ligand-specific and stereoselective actions in vivo. Pharmacological Reviews 2006; 58: 463-519). FPR2 transduces anti-inflammatory effects of LXA4 in many systems, and has been shown to play a key role in the resolution of inflammation (Dufton N, Perretti M. Therapeutic anti-inflammatory potential of formyl peptide receptor agonists. Pharmacology & Therapeutics 2010; 127: 175-188). FPR2 knockout mice show exaggerated inflammation in disease conditions as expected by the biological role of the receptor (Dufton N, Hannon R, Brancaleone V, Dalli J, Patel H B, Gray M, D'Aquisto F, Buckingham J C, Perretti M, Flower R J. Anti-inflammatory role of the murine formyl-peptide receptor 2: Ligand-specific effects on leukocyte responses and experimental inflammation. Journal of Immunology 2010; 184: 2611-2619).
Activation of FPR2 by lipoxin A4 or its analogs and by Annexin I protein has been shown to result in anti-inflammatory activity by promoting active resolution of inflammation which involves inhibition of polymorphonuclear neutrophils (PMNs) and eosinophils migration and also stimulate monocyte migration enabling clearance of apoptotic cells from the site of inflammation in a nonphlogistic manner (Maderna P, Cottell D C, Toivonen T, Dufton N, Dalli J, Perretti M, Godson C. FPR2/ALX receptor expression and internalization are critical for lipoxin A4 and annexin-derived peptide-stimulated phagocytosis. FASEB 2010; 24: 4240-4249; Reville K, Cream J K, Vivers S, Dransfield I, Godson C. Lipoxin A4 redistributes Myosin IIA and Cdc42 in macrophages: Implications for phagocytosis of apoptotic leukocytes. Journal of Immunology 2006; 176: 1878-1888). In addition, FPR2 has been shown to inhibit NK cytotoxicity and promote activation of T cells which further contributes to down regulation of tissue damaging inflammatory signals. FPR2/LXA4 interaction has been shown to be beneficial in experimental models of ischemia reperfusion, angiogenesis, ocular inflammation such as endotoxin-induced uveitis, and corneal wound healing (Serhan C. Resolution phase of inflammation: Novel endogenous anti-inflammatory and proresolving lipid mediators and pathways. Annual reviews of Immunology 2007; 25: 101-137; Medeiros R, Rodrigues G B, Figueiredo C P, Rodrigues E B, Grumman A Jr, Menezes-de-Lima 0 Jr, Passos G F, Calixto J B. Molecular mechanisms of topical anti-inflammatory effects of lipoxin A(4) in endotoxin-induced uveitis. Molecular Pharmacology 2008; 74: 154-161; Gronert K, Maheshwari N, Khan N, Hassan I R, Dunn M, Schwartzmann M L. A role for the mouse 12/15-lipoxygenase pathways in promoting epithelial wound healing and host defense. Journal of Biological Chemistry 2005; 280: 15267-15278; Leedom A, Sullivan A B, Dong B, Lau D, Gronert K. Endogenous LXA4 circuits are determinants of pathological angiogenesis in response to chronic injury. American Journal of Pathology 2010; 176: 74-84; Gronert K. Lipoxins in the eye and their role in wound healing. Prostaglandins, Leukotrienes and Essential fatty Acids. 2005; 73: 221-229). Pharmaceutical utility of lipoxin A4 and its analogs are hampered by inherent physicochemical properties of the natural poly-olefinic natural product. Therefore, small molecule anti-inflammatory agonists of FPR2 would have a wide variety of therapeutic benefit in inflammatory disorders especially in the eye. Targeting FPR2 selectively would also have benefits of reduced side effects as compared to more broad acting anti-inflammatories such as steroids or NSAIDs which have significant side effects of elevated IOP and delays in wound healing in the eye. FPR2 is also expressed in ocular tissues in the cornea and also the posterior of eye, in addition to the inflammatory cells that migrate into the ocular tissues. FPR2 thus represents an important novel pro-resolutionary molecular target for the development of new therapeutic agents in ocular diseases with excessive inflammatory responses.